Question

question 3 of 10 which sentence best describes the production of atp by the light reactions? a. photons of light are absorbed by atp synthase and cause phosphate groups to be added to adp molecules. b. energized electrons from chlorophyll provide the energy needed to combine phosphate groups and adp molecules. c. hydrogen ions (h+) build up inside the thylakoids and flow through atp synthase, causing phosphate groups to be added to adp. d. adp molecules flow through atp synthase, causing them to combine and form atp molecules.

Explanation:

In the light - reactions of photosynthesis, hydrogen ions ($H^+$) accumulate inside the thylakoids. These ions flow through ATP synthase via chemiosmosis. As they do so, the enzyme catalyzes the addition of a phosphate group to ADP to form ATP. Option A is incorrect as photons are not absorbed by ATP synthase. Option B is inaccurate as it's the proton - motive force from the $H^+$ gradient, not just energized electrons directly, that drives ATP synthesis. Option D is wrong as it's the $H^+$ flow through ATP synthase that drives the reaction, not ADP flow in that way.

Answer:

C. Hydrogen ions ($H^+$) build up inside the thylakoids and flow through ATP synthase, causing phosphate groups to be added to ADP.